<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        var arr = [];
        var arr2 = [];
        var sum = 0;
        for (var i = 1; i <= 30; i++) {
            var a = i * 2;
            arr.push(a);
            sum += a;
            if (i % 5 == 0) {
                var pp = sum / 5;
                arr2.push(pp);
                sum = 0;
                arr = [];
            }
        }
        // console.log(arr);
        console.log(arr2);
    </script>
</body>

</html>